1. Field of the Invention
This invention relates in general to obstetrical instruments and more particularly to an obstetrical instrument for rupturing the amniotic membrane.
2. Description of the Prior Art
The amniotic membrane is the sac enclosing the fetus. Frequently, during labor, the physician will rupture the membrane at the opening of the cervix to permit some of the fluid to be drained from the uterus so that the contracting muscles are able to push the baby through the cervical canal.
One commonly used device for performing the amniotomy is a straight rigid plastic rod about 10 inches long. The rod has a hook on one end. The operation is cumbersome and two hands are required in order to perform the rupturing. Another common method employs a clamp, which tears the membrane. Again the operation is cumbersome due to requiring both hands.
There have been several other proposals for devices for performing amniotomy. In U.S. Pat. No. 3,587,591, issued to Satterwhite, a blade is enclosed in a sheath on the top or dorsum of one of the finger members of a surgical glove. The index finger advances the blade from a retracted position to an extended position. One disadvantage of this instrument is the complexity of manufacturing it. Also, the blade is not retractable, thus could lacerate other tissue during withdrawal.
In U.S. Pat. No. 3,126,890, issued to Deming, Sr., a tooth with a sharp point is formed on the palm portion or palmer aspect of one of the finger members of a glove. The disadvantage of this device is that the operator is unable to make a preliminary examination with his finger tips. Also the tooth does not retract.
In U.S. Pat. No. 3,687,139, issued to Poirier, a rigid metal tube is inserted over the physician's finger. This tube has a sharply tipped hook that may be manipulated from a retracted position to the extended position. However, examination by the fingertips of the physician will be prevented by the tube because of the tube's thickness and rigidity.